Stockbyte/Thinkstock(JAMLAH, Syria) -- Twenty U.N. peacekeepers on the Syrian side of Golan Heights have been detained by a group of armed rebel fighters, the United Nations said today.

A spokeswoman for Secretary General Ban Ki Moon said in a statement that the observers -- reportedly from the Philippines -- were on a regular supply mission and were stopped near an observation post that had been damaged during heavy fighting in the nearby village of Jamlah.

The U.N. convoy was taken by a group known as the Yarmouk Martyrs Brigade. The group says they will hold the observers until the Syrian army withdraws from the outskirts of Jamlah.

"If no withdrawal is made within 24 hours we will treat them as prisoners," a rebel spokesman said in a video posted online. The rebels have not threatened to kill the U.N. observers, and for now are treating them “as guests in our village.”

"The members of the Security Council demanded the unconditional and immediate release of all the detained U.N. peacekeepers and called upon all parties to cooperate with UNDOF in good faith to enable it to operate freely and to ensure full security of its personnel," a U.N. spokesperson said.